Development of hybrid 3D-printed structure with aligned drug-loaded fibres using in-situ custom designed templates

Fibre alignment technology is crucial in various emerging applications, such as drug delivery systems, tissue engineering, and scaffold fabrication. However, conventional methods have limitations when it comes to incorporating aligned fibres into 3D printed structures in situ. This research demonstrates the use of custom-designed templates made with conductive ink to control the alignment of drug-loaded polymer fibres on a 3D printed microscale structure. Three different geometries were designed, and the effects of the template on fibre diameter and pattern were investigated. The hybrid structure demonstrated successful control of aligned fibres on printed structures using grounded conductive ink geometric electrodes, as confirmed by SEM. All three custom-designed templates presented unique geometric alignments and fibre diameters of around 1 μm. Additionally, the different collector shapes had an impact on the distribution of fibre diameters. FTIR and EDX analyses concluded that the drug was effectively encapsulated throughout the fibres. In-situ deposition of fibres onto the 3D printed structure enhanced the mechanical properties, and water contact angle results showed that the hybrid structure transitioned to a hydrophilic state with the addition of fibres. A drug delivery study confirmed that the hybrid structure functions as a steady release system, following a Korsmeyer-Peppas kinetic release model. TGA results indicated that the samples are thermally stable, and DSC analysis concluded that the samples were homogeneously produced. The results obtained from the hybrid structures provide a novel mechanism for integrating aligned fibres and 3D printed structures for development in fields such as biomedical engineering, regenerative medicine, and advanced manufacturing.</p

The Use of Electrospun Soy Protein Isolate/Polyvinyl Alcohol Nanofibers for Controlled Drug Delivery As Well As Investigation Into Mass Production

As the global movement progresses towards environmental awareness, industries are attempting to become less dependent on petroleum based materials. This study investigates the incorporation of Soy Protein Isolate (SPI) into nanofibers and their potential applications. Initially mechanical testing was conducted; it was found that at 1:1 ratio of SPI to polymer (PVA) was optimal. For drug release test, SPI based nanofibers were tested via three formulations including nanoparticle implementation. Results observed that loading the drug onto the nanoparticle showed sustained release, ~67% release at 70 hours. Mathematical models of both diffusion and erosion confirmed experimental findings. SPI based nanofibers were then utilized to deliver the antibacterial substance silver acetate, nanofibers were made from solutions containing various concentrations. Results showed increase in bacterial killing activity as silver concentration increased (0-1.5%). Lastly SPI based nanofibers were mass produced with a needleless electrospinning machine, linking the developed technology to potential industrial application

TEchMA2020: 3rd International Conference on Technologies for the Wellbeing and Sustainable Manufacturing Solutions: book of abstracts

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Carbon Fiber Reinforced Lithium-Ion Battery Composites with Higher Mechanical Strength: Multifunctional Power Integration for Structural Applications

Indiana University-Purdue University Indianapolis (IUPUI)This study proposes and evaluates a multi-functional carbon fiber reinforced composite with embedded Lithium-ion battery for its structural integrity concept. The comparison of versatile composite structures manufactured conventionally, air-sprayed and electrospun multi walled carbon nano tubes in order to discover a better packaging method for incorporating lithium-ion batteries at its core is determined. In the electrospinning process recognized globally as a flexible and cost-effective method for generating continuous Nano filaments. It was incorporated exactly on the prepreg surface to obtain effective inter-facial bonding and adhesion between the layers. The mechanical and physical properties of carbon fiber reinforced polymers (CFRP) with electrospun multi walled carbon nano tubes (CNTs) have evidenced to possess higher mechanical strength incorporated between the layers of the composite prepreg than the traditional CFRP prepreg composite, At the same time the air sprayed CFRP with CNTs offers mechanical strength more than the traditional CFRP prepreg but lesser than the electrospun. This can be a design consideration from the economic feasibility viewpoint. They also contribute to efficient load transfer and structural load bearing implementation without compromising the chemistry of battery. The design validation, manufacture methods, and experimental characterization (mechano-electrical) of Multi-functional energy storage composites (MESCs) are examined. Experimental results on the electrochemical characterization reveal that the MESCs show comparable performance to the standard lithium-ion pouch cells without any external packaging and not under any loading requirements. The mechanical performance of the MESC cells especially electrospun CFRP is evaluated from three-point bending tests with the results demonstrating significant mechanical strength and stiffness compared to traditional pouch cells and conventional, air-sprayed CFRP and at lowered packaging weight and thickness. This mechanical robustness of the MESCs enable them to be manufactured as energy-storage devices for electric vehicles

DESIGN OF EXPERIMENTATION TO SYSTEMATICALLY DETERMINE THE INTERACTION BETWEEN ELECTROSPINNING VARIABLES AND TO OPTIMIZE THE FIBER DIAMETER OF ELECTROSPUN POLY (D,L-LACTIDE-CO-GLYCOLIDE) SCAFFOLDS FOR TISSUE ENGINEERED CONSTRUCTS

Cardiac disease causes approximately a third of the deaths in the United States. Furthermore, most of these deaths are due to a condition termed atherosclerosis, which is a buildup of plaque in the coronary arteries, leading to occlusion of normal blood flow to the cardiac muscle. Among the methods to treat the condition, stents are devices that are used to restore normal blood flow in the atherosclerotic arteries. Before advancement can be made to these devices and changes can be tested in live models, a reliable testing method that mimics the environment of the native blood vessel is needed. Dr. Kristen Cardinal developed a tissue engineered blood vessel mimic to test intravascular devices. Among the scaffolding material used, electrospun poly (lactide-co-glycolide) (PLGA) has been used as an economic option that can be made in house. PLGA is a biodegradable co-polymer, and when electrospun, creates a porous matrix with tailorable properties. Currently, the standard PLGA electrospinning protocol produces consistent fibrous scaffolds with a mean fiber diameter of 5-6 microns. Research indicates that cell adhesion is more successful in fibrous matrices with a mean fiber diameter at the nanometer level. However, because previous work in the Tissue Engineering Laboratory at Cal Poly sought to ensure a consistent fibrous, there was no model or equation to determine how to change the electrospinning parameter settings to create scaffolds with an optimal mean fiber diameter. To fill this need, biomedical engineering senior Steffi Wong created a design of experiment to systematically approach the electrospinning variables and determine how they interacted with each other, as well as their effect on fiber diameter. The aims of this thesis were to perform the said design of experiments and determine a model to predict the resulting mean fiber diameter of a scaffold based on the electrospinning parameters as well as to determine what combination of parameters would lead to a scaffold with an optimal mean fiber diameter between 100-200 nanometers. The variables tested were solution concentration, gap distance, flow rate, and applied voltage. Each scaffold was imaged and a mean fiber diameter was calculated and used as the predicted variable in a regression analysis, with the variables indicated above as the predictors. The goal of 100-200 nanometer mean fiber diameter was not reached. The smallest mean fiber diameter calculated was 2.74 microns—half of that of the standard protocol. The regression analysis did result in a model to describe how the voltage, gap distance, and flow rate affected the fiber diameter

Advanced electrospinning apparatus for control, alignment and coating

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThe work contained within this thesis is concerned with the further innovation and the development of apparatus for the electrospinning method which in its most basic form is used to produce and deposit small diameter fibres of many polymers and other materials in a mat structure with random orientation of the deposited fibres. The focus of the innovation is concerned with expanding the ways of collecting these fibres by implementing newly developed techniques, building upon the conventional electrospinning technique and literature to create an advanced electrospinning system. The innovation can be split into the following areas of study: Development of apparatus for the control of the electrospinning process, apparatus for the control of the deposition of the fibres and the development of apparatus for coating conductive wires and other materials with electrospun polymer fibres. Each of the apparatus designed and tested within this work build upon previous examples of experimental apparatus created by other groups as discussed in the following chapters. The apparatus developed and described is a combination of incremental improvement and previously untried combinations of the work that as gone before. All the apparatus developed for use as part of the ectrospinning process were designed to be easily improved incrementally and the development cycles to achieve the final apparatus shown have also been included. The novelty within this work is concerned the development of apparatus for use with the electrospinning process and with the overall supporting systems that have been developed alongside them. The novelty of the apparatus used in conjunction with the electrospinning process includes a remotely controlled fibre printer that can print tracks of electrospun fibres creating shapes and patterns. The development of the apparatus is discussed in detail covering all mechanical and electronic considerations and design decisions. The final apparatus is shown to operate as desired with polymer tracks thicknesses of 20mm in width achieved. A novel apparatus was developed using multiple ground electrodes that were digitally controlled in conjunction with the electrospinning method to achieve a new method of layering aligned fibres in layers with alternating orientations. Also the apparatus can be used in an alternate mode which allows the selective electrospinning of aligned bundles of fibres between multiple electrodes in user defined patterns. The apparatus is shown to achieve good polymer fibre alignment between electrodes and also is shown to work as deigned in regard to the layering of the aligned fibres. An alternate way of using the apparatus is successfully demonstrated allowing the selective patterning of deposited fibre bundles between multiple electrodes. A polymer coating apparatus was also developed to extend the electrospinning method to create core-shell fibres as part of a larger system developed for creating smart textiles and fibrous sensors. The novel electrospinning apparatus is shown to be able to uniformly coat both the circumference and along the length over a comparatively long length of core-shell fibre. A deposition thickness of polymer between 36 μm and 242 μm was achieved by changing the coating speed. An alignment of the electrospun fibres along the length on the core wires is also shown and discussed. The core-shell fibres developed are used in conjunction with another developed apparatus piece that weaves a series of wires around the outer shell to create a three layer device consisting of an outer electrically conductive layer, an electrospun polymer layer and an electrically conductive core. The system is shown to successfully create these three layer devices

Viscoelastic Modeling of Stress Relaxation Behavior in Biodegradable Polymers

Regenerating tissues using biodegradable structures onto which cells attach, populate, and synthesize new tissue or a whole organ has become more essential due to the scarcity in donor transplants. The biodegradable structures from various animal tissues such as skin, bladder, fat and intestine have seen clinical usage due to the advantage of premade architecture, which is conducive for tissue regeneration. However, manipulating these architectures to grow other tissues has shown many obstacles. Hence, synthesizing matrixes of both synthetic and natural polymers should possess bioactivity along with high porous structures to aid cell in-growth and mechanical strength to withstand the stresses and strains in the body. Biological tissues exhibit viscous (like fluids) and elastic (like solids) behavior, hence, prepared materials should have similar characteristics.Previously we have reported on the stress relaxation characteristics of poly-lactic-co-glycolic acid (PLGA) films [1], polycaprolactone (PCL) films [2] and chitosan, chitosan-gelatin porous structures [3] formed by freeze-drying. We have also modeled some of the behavior using quasi-linear viscoelastic model and pseudo component models. The objective of this study was to evaluate and model the effect of processing scaffolds in viscoelastic behavior and also to compare the relaxation characteristics of polymers as different structures (scaffolds and films). For this purpose, we prepared PCL scaffolds by salt leaching technique and electrospun technique; chitosan, chitosan-gelatin films by air drying technique. First, uniaxial tensile properties were evaluated under physiological conditions (hydrated in phosphate buffered saline at 37 &#61616;C). From the estimated break strain, the limit of strain per ramp was calculated and stretched. The ramp-and-hold type of stress relaxation test was performed for five successive stages.We developed two models using (i) 5- parameter model (containing two components with a hyper-elastic spring and suitable pseudo component) and (ii) 8- parameter model (containing three components with a hyper-elastic spring and two suitable pseudo components) in Visual Basic Applications accessed through MS Excel. The models were used to fit the experimental stress-relaxation data and parameters were obtained to understand the influence of porous architecture. To validate the utility of the models, obtained parameters were used to predict cyclic behaviors, which were compared independently with the cyclical experimental results. These results showed the model could be used to predict the cyclical behavior under the tested strain rates.Chemical Engineerin

An investigation of yarn spinning from electrospun nanofibres

The aim of the thesis is to investigate yarn spinning from electrospun nanofibres. The concepts of staple and core yarn spinning on electrospun nanofibres has been investigated by examining nanofibre uniformity, alignment, twist insertion and yarn take up by engining and engineering a new take up mechanism. Nylon 6 nanofibres have been fabricated and used throughout this work. The effects of varying the electrospinning parameters such as applied voltage, polymer solution concentration and electrospinning distance on fibre morphology have been established for process optimization. A novel nanofibre aligning mechanism has been devised and systematically revised to enable optimization of alignment process parameters. MWCNTs have been successfully dispersed into nylon 6 nanofibres and have been aligned along the nanofibre body by manipulating the electric and stretching forces with the aid of the alignment mechanism. Novel mechanisms for spinning continuous twisted nanofibre/composite nanofibre yarn and core electrospun yarn have been researched, developed and implemented by making samples. It has been found that defining the velocity and count of the nanofibres entering the spinning zone is important for controlling the yarn count and twist per unit length. By modelling the electrospinning jet, mathematical equations for theoretically calculating the velocity of the jet and nanofibres and their count have been established, necessary for process control. Aspects of practical measurement and comparison of jet and nanofibre velocities have been described and discussed. Tensile testing of single nanofibre and nanofibre mats has been attempted for mechanical characterization. Initial results show the range of tensile strength of nylon 6 nanofibre assemblies and indicate the effect of change of process parameters. A review of those engineering mechanisms related to various nanofibre architectures and their industrial and commercial importance has also been reviewed, described and discussed

Computational methods to engineer process-structure-property relationships in organic electronics: The case of organic photovoltaics

Ever since the Nobel prize winning work by Heeger and his colleagues, organic electronics enjoyed increasing attention from researchers all over the world. While there is a large potential for organic electronics in areas of transistors, solar cells, diodes, flexible displays, RFIDs, smart textiles, smart tattoos, artificial skin, bio-electronics, medical devices and many more, there have been very few applications that reached the market. Organic photovoltaics especially can utilize large market of untapped solar power -- portable and affordable solar conversion devices. While there are several reasons for their unavailability, a major one is the challenge of controlling device morphology at several scales, simultaneously. The morphology is intricately related to the processing of the device and strongly influences performance. Added to this is the unending development of new polymeric materials in search of high power conversion efficiencies. Fully understanding this intricate relationship between materials, processing conditions and power conversion is highly resource and time intensive. The goal of this work is to provide tightly coupled computational routes to these expensive experiments, and demonstrate process control using in-silico experiments. This goal is achieved in multiple stages and is commonly called the process-structure-property loop in material science community. We leverage recent advances in high performance computing (HPC) and high throughput computing (HTC) towards this end. Two open-source software packages were developed: GRATE and PARyOpt. GRATE provides a means to reliably and repeatably quantify TEM images for identifying transport characteristics. It solves the problem of manually quantifying large number of large images with fine details. PARyOpt is a Gaussian process based optimization library that is especially useful for optimizing expensive phenomena. Both these are highly modular and designed to be easily integrated with existing software. It is anticipated that the organic electronics community will use these tools to accelerate discovery and development of new-age devices